Bulky yarn



p 1961 T B. DAVENPORT ETAL 2,999,351

BULKY YARN Filed July 17, 1956 IIIIIIIIIIIIIIl INVENTORS T. B. DAVENPORTBY ALFRED 6. NEW

ATTORNEY 2,999,351 BULK! YARN T B. Davenport and Alfred G. New,Greeuville, 8.6., as-

signors to Deering Millikan Research \Corporation, 'lendleton, Sail, acorporation of Delaware Filed July 17, 1956, Ser. No. 593,353 7 Claims.(Cl. 57-149) This invention relates to thick and thin filamentary yarns,and to methods and apparatus for producing the same.

Thick and thin staple fiber yarns are well known and widely employed inthe textile industry for the production of novelty fabrics. Staple fiberyarns cannot, however, be readily employed for the weaving or knittingof sheer fabrics and in some instances do not have as high a strength toweight ratio as is desired. For these reasons, numerous efforts havebeen made to develop suitable procedures for the manufacture of thickand thin continuous filament yarns, but as yet no method has beendeveloped which is satisfactory in all respects.

The only method for producing a thick and thin continuous filament yarnwhich has achieved any degree of commercial success comprises varyingthe rate of extrusion during the original spinning operation so that thefilaments in the extruded yarn have longitudinal fluctuations indiameter. This procedure has several severe disadvantages. In the firstplace, use of the process is limited to the yarn manufacturer and cannotbe readily performed by the yarn user. This means that the weaver orknitter must place his order for the specially extruded yarn long inadvance of the time when the yarn is actually needed and that he cannotvary the length or character of the slubs to suit his own taste andneeds as they arise. A further disadvantage of this prior art process isthat specially extruded yarns are generally expensive and this limitstheir use in the commercial manufacture of many fabrics. Still anotherdisadvantage of the variable rate extrusion process for the manufactureof thick and thin continuous filament yarns is that it is frequentlyimpossible to obtain a slub differing sufliciently in size and texturefrom the thin portion of the yarn to result in the slub being asapparent as is desired in a finished fabric. This is because there issubstantially no difference in the bulking characteristics of the thickand thin portions of the yarn and the difference in appearance mustresult entirely from the variations in diameter of the componentfilaments.

It is an object of this invention to provide a versatile method forproducing a thick and thin continuous filament yarn that can bepracticed by the textile fabricator and that permits the fabricator toreadily vary the length and nature of the slubs to suit his immediateneeds and desires.

It is another object of this invention to provide a thick and thincontinuous filament yarn in which the slubs are of such nature that whenthe yarn is formed into cloth, the slubs are readily apparent regardlessof the angle from which the surface of the cloth is viewed. The slubs inthe novel yarns of this invention are due to an increased localizedtendency of the yarn to bulk rather than to increased diameters of theyarn filament, and since the highly bulked yarn segments have anentirely diiferent luster than the remainder of the yarn, a fabric wovenof yarns according to this invention has an exceedingly novel andattractive appearance.

According to this invention there is provided a multifilament yarn,formed from a heat-settable material, which has had imparted thereto aset tendency to twist with spaced lengths of the yarn being detwisted inopposition to this tendency and having not more than about 15 turns oftwist per inch. The portions of the yarn disposed between these spacedlengths remain in a relatively highly twisted condition such that theycontain at least about 20 turns of twist per inch and preferably suchthat there is at least about 20 turns or more of twist per inchdifferential between the spaced lengths of substantially completelydetwisted yarn and the relatively highly twisted segments. The torquetendencies set into the yarn filaments cause them to form into loops,snarls and curls at the points where the yarn is substantiallycompletely detwisted so that the. yarn at these points is highly bulked,while the high twist in the yarn segments intermediate the detwistedportions retains thehighly twisted segments in a compacted condition.This differential bulking is apparent to a very pronounced extent whenthe yarn is formed into fabric.

Two generally similar but slightly different procedures for making thenew yarns have also been discovered and it is intended that theyconstitute a part of the invention. The first and generally preferredprocedure comprises imparting to the yarn a longitudinally uniform settendency to twist and thereafter detwisting spaced lengths of the yarnto a much greater extent than the remaining portions of the yarn. Analternative procedure comprises twisting a multi-filament strand in sucha manner that spaced lengths thereof are twisted to a less extent thansegments of the yarn between the spaced lengths, setting the twist andthereafter uniformly detwisting to such an extent as to substantiallyuntwist the spaced lengths of yarn previously containing only a lowamount of twist so that the intermediate portions of the yarn remain ina highly twisted condition. It will be seen that by either procedure oneobtains a yarn having alternating highly twisted portions andsubstantially completely detwisted segments.

It has been previously suggested that yarns be differentially twistedfor the purpose of producing fabrics with novel surface effects. Suchyarns are, however, generally suitable only for producing variable crepeeffects and it is not possible to produce a satisfactory thick and thinyarn by a simple diflerential twist procedure. A first reason why thisis true is that if one attempts to limit the high twist to only a shortsegment of the yarn, such as would be necessary in making a slubbedyarn, the twist tends to equalize during weaving so that substantiallyno surface efiect at all is obtained. Another reason why a simpledifferential twist procedure is not satisfactory for producing a thickand thin yarn is that little or no differential bulking can be achievedby this procedure.

It is a surprising feature of this invention that there is substantiallyno tendency for twist in the yarn to equalize in winding and weavingoperations conducted with the yarn after its manufacture. This isapparently because the filaments in the detwisted segments of the yarnrespond individually to the torque set into the yarn and form intoloops, curls and snarls. This serves to partially relax the stresses inthe yarn so that there is a reduced tendency for the yarn, at the pointswhere it is untwisted, to return to a highly twisted condition. At thesame time, the formation of the filaments into loops, snarls, and thelike results in the detwisted segments of the yarn becoming highlybulked and the bulked nature of the detwisted segments also serves toprevent twist from passing into these segments of the yarn as a resultof twist equalization.

it is a feature of the new process that it can be employed withmulti-filament yarns formed from any heatsettable material andillustrative examples of filamentary yarns which can be suitablyemployed in the new process include yarns made from nylon, polyestermaterials such as glycol terephthalate, and acrylic materials such aspolymers of acrylonitrile or co-polymers of acrylonitrile with otherpolymerizable monomers. Nylon yarns are preferred since cold flow inthese yarns is negligible and since they are capable of taking anexcellent set. The new process can be employed with almost any size ofyarn and denier per filament may vary Within wide limits. For example,the total denier of the yarn may vary from about 20 denier or less toabout 200 denier or more and the denier per filament may vary about 1to- 20. As a general rule, each end of the yarn to be processed shouldbe composed of at least -about'5 to- 7 filaments and yarns composed ofat least about 10 to filaments are generally preferred. This is becausethe degree of bulking in the detwisted segments increases with anincrease in the number of filaments in the yarn.

The first twisting operation is preferably performed on an tip-twisterand according to a preferred procedure, the yarn is initially twisted ina uniform manner to at least about 38. and. preferably to about 60 to160 turns per inch. The greater the amount of twist inserted into theyarn at this point, the greater is the bulking effect obtained in spacedsegments of tne yarn when they are subsequently detwisted. According toan alternative pro cedure, the amount of twist inserted in the originaltwisting operation is varied, for example by momentarily stopping orreducing the rate of rotation of the take-up package, so that spacedlengths of the yarn are twisted to a lesser extent than the remainingportions of the yarn. However, even the portions of the yarn containing'the smaller amount of twist should be highly twisted, or in other wordsshould contain at least about 30 turns of twist per inch and shouldpreferably contain at least about 40 to 60 turns per inch of twist. Thetwist differential between the highly twisted and the lesser twistedportions of the yarn should be at least about to 30 turns.

The heat setting operation to set the original twist into the yarn canbe conducted in a conventional manner, for example, with super heatedsteam. As a general rule, one should employ a heat-setting temperatureof at least about 230 F. and temperatures of from about 240 F. to 280 F.are generally preferred. The time required for an adequate set isgenerally only 10 to 20 minutes although the yarn can be retained at aheat-setting temperature for longer periods of time if desired.

The detwisting operation is also preferably performed on an up-twistermachine. If the original twisting operation was uniform in nature, thedetwisting operation must be irregular to provide the sections of yarnof lower and higher twist. This can readily be achieved by periodically"arying the rate of take-up. if the original twisting operation wasirregular in nature, the detwisting operation can be conducted in auniform manner since the yarn is already provided with sections of lowerand higher twist. The detwisting operation should be conducted to anextent such that spaced lengths of the yarn have not more than about 15and preferably not more than about 10 turns per inch of twist so thatthese portions of the yarn are free to bulk to a near maximum extent. Asa general rule the smaller the amount of twist in these portions of theyarn, the greater is the slub effect obtained. The remaining portions ofthe yarn should contain at least about 20 turns of twist to hold theyarn in a highly compacted condition at points intermediate thesubstantially completely detwisted segments, and for best results thereshould be about 20 and preferably at least about 40 turns of twist perinch differential between the substantially completely detwistedsegments and the more highly twisted portions of the yarn.

The invention will now be described with reference to the accompanyingdrawings in'which:

FIGURE 1 is a schematic view in perspective of one form of apparatussuitable for manufacturing the yarns of the invention;

FIGURE '2. is an. enlargedfront plan view, partially i in section, of aportion of the apparatus schematically illustrated in FIGURE 1;

FIGURE 3 is a fragmentary plan view of a novel yarn according to thisinvention.

With reference to FIGURES l and 2 in greater detail, there isillustrated a conventional up-twister spindie It journaled in a twisterframe, not illustrated, and provided witha whorl pontion 12..Conventional means are provided for rapidly rotating the spindle l0 andmay, for example, comprise a belt 14 running about a plurality ofpulleys, one of which is illustrated at 16, and contacting the whorlportion 12 of spindle it).

Carried by spindle 10 is a conventional spool or bobbin 18 containing asupply of yarn 2i} and journaled about the upper extremity of spindle itimmediately above the upper head of bobbin 1-8 is i'lyer 22 which may beconventional in form. The flyer 22 operates in a well known manner toguide an end of yarn 23 rom bobbin 1-8 to an apex guide 24 positioned onthe extended axis of rotation of the spindle 10.

The reference numeral 26 designates a conventional takeup spool whichmay be driven by any suitable means, for example, by means of a surfacecontact roll 28. Roll 28 is illustrated as being driven from pulley 16through a slip clutch, generally indicated by the reference numeral 30,or through an electromagnetic clutch, generally indicated by thereference numeral 32. Both slip clutch 3t and electromagnetic clutch 32,which may, in each instance, be of conventional design, are carried by asingle shaft 34 and are driven from a single shaft 36. The slip clutch30 is driven by means of a first gear 38, carried by shaft 36, a chain40, and a gear 42 carried by the driving element 43 of the clutch 30,while the electromagnetic clutch 32 is driven by means of a gear 44,carried by shaft 36, a chain 46, and a gear 48 carried by the drivingelement 49 of the electromagnetic clutch. The shaft 36 is illustrated asbeing driven through bevel gears 50 and 51 and a shaft 52 but may bedriven in timed relationship to the spindle 10 by any suitable means.

The driving element 43 of slip clutch 313 is journaled for free rotationabout shaft 34 by means of antifriction bearings such as ball bearings54 (FIGURE 2) and the riving element 49 of electromagnetic clutch 32 islikewise journaled for free rotation about shaft 34 by means ofantifriction bearings, one of which is shown at 56. The driven elementof slip clutch 30, indicated by the reference numeral 58, and the drivenelement of electromagnetic clutch 32, indicated by the reference numeral60, are, in each instance, keyed to shaft 34 and rotate in fixedrelationship therewith. The gear 42 is relatively large as compared togear 38, so that when the electromagnetic clutch 32 is disengaged, theshaft 34 is driven at a relatively low speed through slip clutch 30. Thegear 48 is relatively small as compared to gear 44 so that when theelectromagnetic clutch 32 is engaged, it over-powers slip clutch 30 andthe shaft 34 is rotated at a relatively high rate of speed. The shaft 34drives roll 28 by means of gears 62, 63, and 64 and a shaft 65, so thatthe yarn take-up rate is proportional to the rate of rotation of shaft34.

The reference numeral 66 generally indicates a source of electricalimpulses which is here schematically illustrated as comprising aconventional phonograph record player. The record player 66 is providedwith a record 68 transcribed with a series of high frequency signalimpulses which are preferably of constant duration but which maysuitably be either of random or patterned occurrence. The transcribedsignals on record 68 are used to produce a high frequency alternatingelectric current by means of play-back head 70 and the electric currentis transmitted through leads 71 and 72 to a conventional amplifierschematiclly illustrated at 74. The amplified signal is fed throughleads 75 and 76 to an electromagnetic relay '78 which controls a flow ofdirect current from any suitable source, not illustrated, to clutch 32through a pair of leads 79 and 80.- A selector switch 82 is preferablyprovided so that activation of relay 78 can either interrupt or initiatethe flow of direct current to clutch 3-2 and thereby deactivate oractivate clutch 32 as desired.

The reference numeral 84 generally indicates a pair of nip rolls whichare here illustrated as being freely rotatable but which may be drivenin timed relationship to the roll 28 if desired. The rolls 84 serve toprevent the twist inserted in yarn end 23 by spindle from running alongthe yarn to the take-up package 26, when short length slubs are desired,and result in a more elfective localization of the twist in thedifferentially twisted portions of the yarn. Means, not illustrated, arepreferably provided for changing the position of rolls 84 relative tothe take up roll 26 and for removing the rolls 74 from operativeposition when long slubs are desired.

In operation, an end of yarn from package 18 is threaded through fiyer22, guide 24 and passed between rolls 84 to take-up package 26. If it isdesired that the yarn be uniformly twisted, amplifier 74 is simplydisconnected and selector switch 82 is set to prevent a fiow of currentto clutch 32. The take-up spool 26 is then driven at all times throughslip clutch 30. If it is desired that the yarn be intermittentlytwisted, amplifier 74 is energized, record player 66 is placed inoperation, and selector switch 82 is set so that relay 78 intermittentlysupplies direct current to clutch 32. When the clutch 32 is suppliedwith a fiow of direct current, the clutch becomes engaged, the rate ofrotation of shaft 34 increases and the yarn end 23 between rolls 84 andflyer 22 is twisted to a less exent than would be the case if take-uproll 26 were being rotated at its normal rate.

According to the preferred procedure outlined above, the first twistingoperation is preferably conducted with record player 66 inoperative andwith clutch 32 disengaged. A gear ratio is then selected to provide fora rate of rotation of roll 28 relative to the rate of rotation ofspindle 10 such that from about, for example, 50 to 100 turns per inchof twist are inserted into the yarn end 23. When the supply of yarnoriginally on spool 18 is uniformly twisted and collected on spool 26,the twisted yarn is heat-set and the spool of heat-set yarn is placedupon the spindle 10. The direction of rotation of spindle 10 is thenreversed, the record player 66 is placed in operation and selectorswitch 82 is preferably set so that the flow of direct current to clutch32 is interrupted when a signal is produced by the play-back head 70 andso that clutch 32 is normally engaged. Gears 44 and 48 are selected ofsuch size that when clutch 32 is engaged, the rate of take-up is suchthat the yarn end 23 is only partially detwisted. For example, the ratioof the rate of rotation of spindle 10 to the rate of rotation of roll 28can suitably be such that only about 5 to turns per inch of twist areremoved from the yarn when the take-up device is in normal operationwith clutch 32 engaged. Gears 38 and 42 are selected of such size thatwhen clutch 32 is disengaged, a length of the yarn end 23, correspondingto the length of the slub desired, is substantially complete 1ydetwisted. The length of the detwisted segments is controlled by thelength of the signal fed to relay 78 and can be varied by the use ofrecords having, relative to each other, signal impulses of differentdurations or more satisfactorily by the use of a conventional electronictime delay-relay mechanism to vary the duration of the control impulses.

In some instances slubs of a length equal to only the distance fromflyer 22 to spool 26, or even less, may be desired. Slubs of a lengthequal to the distance from flyer 22 to spool 26 can readily be formed bymoving rolls 84 to an inoperative position and removing chain 40 so thatthe take-up of yarn stops when clutch 32 is de-energized. Shorter lengthslubs can be formed by removing chain 40 and spacing rolls 84 from flyer22 a 6 distance equal to the length of the slub desired. It will beunderstood that in such instances, the length of the signal impulse fedto relay 7 3 and the rate of rotation of spindle 10 must be socorrelated that a length of the yarn, equal to the length of the slubdesired, is substantially completely detwisted.

According to the alternative procedure outlined above, the firsttwisting operation isconducted with record player 66 and amplifier 74 infull operation and preferably with the selector switch 82 set so thatclutch 32 is normally disengaged and so that the clutch becomes engagedwhen a signal is being received by relay 78. Gears are selected suchthat from about, for example, 50 to turns per inch of twist are insertedinto the yarn when clutch 32 is disengaged and such that about 20 to 70turns per inch of twist are inserted when clutch 32 is engaged. When theyarn from spool 18 has been twisted and collected upon spool 26, thetwist in the yarn is heat-set as above and the heat-set yarn is placedon spindle 10. The direction of rotation of the spindle is then reversedand the record player is disconnected so that the clutch 32 remainscontinuously engaged or disengaged as desired depending upon theposition of selector switch 32. A gear ratio is then selected whichresults in the portions of the yarn which received the lower degree oftwist inthe original twisting operation being substantially completelydetwisted but leaves sufiicient twist in the more highly twistedportions of the yarn to prevent bulking thereof.

With specific reference to FIGURE 3 of the drawings, there isillustrated a short length of yarn approximately as it would appear whenprepared by either one of the above two procedures. It will be seen thatat 86, where the yarn is substantially completely detwisted, thefilaments form into curls, kinks and snarls and a noticeable bulking ofthe yarn is achieved. It will also be seen that portions of the yarn,for example, at 88 remain in a twisted condition and are highlycompacted as a result of the twist therein. A thick and thin continuousfilament yarn is thus produced without any substantial change in thediameter of the component filaments.

Having thus described our invention, what we desire to claim and secureby Letters Patent is:

l. A multi-filament thick and thin yarn formed from a heat-settablematerial, said yarn having imparted thereto a set tendency to twist,spaced lengths of said yarn being twisted sulficiently in conformitywith said tendency to prevent any substantial degree of bulking, andsaid yarn having segments, disposed between said spaced lengths, with arelatively lower degree of twist, the individual filaments of the yarnwithin said segments containing loops and kinks which impart a loftynature to the portions of said yarn within said segments.

2. A multi-filament yarn formed from a heat-settable material said yarnhaving imparted thereto a set tendency to twist to the extent of a leastabout 20 turns per inch, spaced lengths of said yarn having not morethan about 15 turns of twist per inch, and said yarn having segments,disposed betweensaid spaced lengths, which are more highly twisted inconformity with said tendency and contain at least about 20 turns oftwist per inch.

3. A multi-filament yarn as in claim 2 wherein the twist difierentialbetween said spaced lengths and said more highly twisted segments is atleast about 20 turns of twist per inch.

4. A multi-filament yarn according to claim 3 wherein the yarn containsat least about 10 filaments per end and is nylon.

5. A multi-filarnent nylon yarn containing at least about 10 filamentsper end and having imparted thereto a set tendency to twist to theextent of at least about 40 turns per inch, spaced lengths of said yarnhaving not more than about 10 turns of twist per inch, and said yarnhaving segments, disposed between said spaced lengths, which are morehighly twisted in conformity with said tendency so that there is atleast about 40 turns of twist per inch differential between said spacedlengths and said highly twisted segments.

6; A yarn according to claim 5 wherein said'space'd lengths are ofsubstantially uniform length but are randomly distributed along thelength of said yarn.

7. intermittently bulked continuous multi-filarnent yarn havingalternately spaced bulked and unbulked segments, there beingsubstantially the same filament quantity in number of filaments and infilament diameter, in both'the bulked and unbulked segments, thefilament portions in said bulked segments being in a relaxedself-straining and self-kinking deformed state and forming substantiallylarger air-filled interstices therebetween than the filament portions ofsaid unbulked segments, the filament portions in said bulked segmentshaving substantial unbalanced internal stresses along their length whichtend to selfestablish a non-linearly deformed'configuration for saidfilament portions when in a relaxed state, said filament portions insaid bulked segments being-torsionallv heatstressed and tending toassume a mechanically selfdeformedkinky configuration.

References Citedin the tile-of this'patent UNITED STATES PATENTS2,061,614 Dickie et a1; Nov; 24; 1936 2,084,975 Katz June 22, 19372,089,193 Dreyfus Aug." 10, 1937 2,104,810 ODowd Jan; ll, 1938 2,293,003Hunter Aug. 11, 1942 2,703,439 Dole et al. Mar. 8; 1955 2,711,627 Lea-thet al. June 28, 1955 2,751,747 Burleson June 26, 1956 2,783,609 BreenMar. 5, 1957 OTHER REFERENCES Stretch and Bulk Yarns, Textile World,June 1955, pp; 94-97 (p. 94, column 3, lines 19-21 pertinent).

Crepe, Crimp and Crinkled Yarn, pp. 398-404, Journal of the TextileInstitute, v01. 46, No. 7, Ju1y'1955 (p. 402, last six lines pertinent).

